U.S. patent number 5,756,178 [Application Number 08/231,697] was granted by the patent office on 1998-05-26 for screw caps and seals for screw caps.
This patent grant is currently assigned to Rical, S.A.. Invention is credited to Jacques Obadia.
United States Patent |
5,756,178 |
Obadia |
May 26, 1998 |
Screw caps and seals for screw caps
Abstract
Composite material for seals of plastic caps, especially of
screw caps, ensuring leakproofing against liquids and
imperviousness to gases at the same time, characterized in that it
comprises, combined in a coherent multilayer structure, at least
one middle layer (4) made of a plastic substance with a gas barrier
effect, with a high modulus of rigidity, two outer layers (7)
arranged on either side of the middle layer and consisting of a
plastic substance with a low modulus of rigidity, each of the outer
layers having a thickness greater than the thickness of the middle
layer, and between the middle layer (4) and each outer layer (7) an
intermediate layer (5) made of a substance of the same class as the
outer layer, but with a high modulus of rigidity.
Inventors: |
Obadia; Jacques (Paris,
FR) |
Assignee: |
Rical, S.A. (Longvic Cedex,
FR)
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Family
ID: |
9446793 |
Appl.
No.: |
08/231,697 |
Filed: |
April 25, 1994 |
Foreign Application Priority Data
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May 5, 1993 [FR] |
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93 05374 |
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Current U.S.
Class: |
428/66.4;
428/212; 428/476.9; 215/347; 215/341; 428/523; 428/518; 428/483;
428/337; 428/215; 428/339; 428/520 |
Current CPC
Class: |
B32B
7/12 (20130101); B32B 27/34 (20130101); B32B
27/304 (20130101); B32B 27/36 (20130101); B32B
27/306 (20130101); B32B 7/02 (20130101); B32B
27/32 (20130101); B32B 27/08 (20130101); Y10T
428/3192 (20150401); Y10T 428/31928 (20150401); B32B
2307/7265 (20130101); B32B 2435/02 (20130101); Y10T
428/24942 (20150115); Y10T 428/215 (20150115); Y10T
428/24967 (20150115); B32B 2307/7242 (20130101); Y10T
428/31938 (20150401); B32B 2309/105 (20130101); Y10T
428/269 (20150115); Y10T 428/266 (20150115); Y10T
428/31797 (20150401); Y10T 428/31757 (20150401) |
Current International
Class: |
B32B
7/02 (20060101); B32B 007/02 (); B32B 025/08 ();
B32B 027/08 (); B32B 027/32 () |
Field of
Search: |
;428/35.4,36.6,36.7,522,518,515,516,523,520,69.1,66.4,212,213,215,332,337,339
;215/341,347,349,350,351,352,217,218,219,220,233,234,271,270,273,292 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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0 288 972 |
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Nov 1988 |
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EP |
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0 306 820 |
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Mar 1989 |
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EP |
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0 530 977 |
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Mar 1993 |
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EP |
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66 379 |
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May 1973 |
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LU |
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1 347 883 |
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Feb 1974 |
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GB |
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Primary Examiner: Thibodeau; Paul J.
Assistant Examiner: Chen; Vivian
Attorney, Agent or Firm: Beveridge, DeGrandi, Weilacher
& Young, L.L.P.
Claims
I claim:
1. Seal member for plastic closure screw caps, providing liquid
sealing and gas imperviousness consisting essentially of a laminate
disc of symmetrical multilayer structure comprising a middle layer
having a thickness of between 100 and 250 .mu.m and made from a
plastic material having a modulus of rigidity of between about 1300
and 2200 MPa and exhibiting a gas barrier effect, and two outer
layers arranged on either side of said middle layer and each having
a same thickness of between 300 and 550 .mu.m and made from a
plastic material exhibiting a modulus of rigidity of between about
100 and 300 MPa, each of said outer layers having an outer surface
which is exposed so that both of said outer surfaces are capable of
contacting and sealing against a neck of a receptacle.
2. Seal member according to claim 1, wherein said middle layer
consists of a sheet selected from the group consisting of
polyethylene terephthalate, polyamide, polyvinylidene chloride and
ethylene/vinyl alcohol.
3. Seal member according to claim 1, wherein each of said outer
layers consists of a sheet of polypropylene elastomer.
4. A plastic closure screw cap which includes a seal member
according to claim 1.
5. A receptacle which is sealed by a plastic closure screw cap,
said screw cap including a seal member according to claim 1, said
receptacle having a neck which is directly contacted by one of said
outer layers of said seal member.
6. Seal member according to claim 1, wherein said multilayer
structure further comprises, between said middle layer and each of
said outer layers, an intermediate layer having a thickness of
between 10 and 50 .mu.m and made of a plastic material of the same
polymer as the outer layers, but exhibiting a modulus of rigidity
of between about 1300 and 2200 MPa, each of said intermediate
layers being joined to said outer layer by calendaring while
heated.
7. Seal member according to claim 6, wherein each of said
intermediate layers consists of a film of polypropylene.
8. Seal member according to claim 6, wherein each of said
intermediate layers is joined to said middle layer with a
polyurethane adhesive.
9. Seal member for plastic closure screw caps, providing liquid
sealing and gas imperviousness consisting essentially of a laminate
disc of symmetrical, multilayer structure comprising:
a middle layer made from a plastic material having a modulus of
rigidity of between about 1300 and 2200 MPa and exhibiting a gas
barrier effect;
two outer layers arranged on either side of said middle layer and
being made from a plastic material exhibiting a modulus of rigidity
of between about 100 and 300 MPa, and
between said middle layer and each of said outer layers, an
intermediate layer made of a plastic material of the same polymer
as the outer layers, but exhibiting a modulus of rigidity of
between about 1300 and 2200 MPa,
the said two outer layers each having a same thickness of between
300 and 550 .mu.m, said middle layer having a thickness of between
100 and 250 .mu.m; said intermediate layers each having a same
thickness of between 10 and 50 .mu.m and being joined to said outer
layers by calendaring while heated, and joined to said middle layer
with a polyurethane adhesive;
each of said outer layers having an outer surface which is exposed
so that both of said outer surfaces are capable of contacting and
sealing against a neck of a receptacle.
10. Seal member according to claim 9, wherein each of said outer
layers consists of a sheet of polypropylene elastomer.
11. A plastic closure screw cap which includes a seal member
according to claim 9.
12. A receptacle which is sealed by a plastic closure screw cap,
said screw cap including a seal member according to claim 9, said
receptacle having a neck which is directly contacted by one of said
outer layers of said seal member.
13. Seal member according to claim 9, wherein said middle layer
consists of a sheet selected from the group consisting of
polyethylene terephthalate polyamide, polyvinylidene chloride and
ethylene/vinyl alcohol.
14. Seal member according to claim 13, wherein each of said
intermediate layers consists of a film of polypropylene.
15. A plastic closure screw cap which includes a seal member which
provides liquid sealing and gas imperviousness, said seal member
consisting essentially of a laminate disc of symmetrical multilayer
structure comprising a middle layer having a thickness of between
100 and 250 .mu.m and made from a plastic material having a modulus
of rigidity of between about 1300 and 2200 MPa and exhibiting a gas
barrier effect, and two outer layers arranged on either side of
said middle layer and each having a same thickness of between 300
and 550 .mu.m and made from a plastic material exhibiting a modulus
of rigidity of between about 100 and 300 MPa, each of said outer
layers having an outer surface which is exposed so that both of
said outer surfaces are capable of contacting and sealing against a
neck of a receptacle.
16. A screw cap according to claim 15, wherein said middle layer
consists of a sheet selected from the group consisting of
polyethylene terephthalate, polyamide, polyvinylidene chloride and
ethylene/vinyl alcohol.
17. A screw cap according to claim 15, wherein each of said outer
layers consists of a sheet of polypropylene elastomer.
18. A receptacle which is sealed by a plastic closure screw cap
according to claim 15, said receptacle having a neck which is
directly contacted by one of said outer layers of said seal
member.
19. A screw cap according to claim 15, wherein said multilayer
structure further comprises, between said middle layer and each of
said outer layers, an intermediate layer having a thickness of
between 10 and 50 .mu.m and made of a plastic material of the same
polymer as the outer layers, but exhibiting a modulus of rigidity
of between about 1300 and 2200 MPa, each of said intermediate
layers being joined to said outer layer by calendaring while
heated.
20. A screw cap according to claim 19, wherein each of said
intermediate layers consists of a film of polypropylene.
21. A screw cap according to claim 19, wherein each of said
intermediate layers is joined to said middle layer with a
polyurethane adhesive.
22. A plastic closure screw cap which includes a seal member which
provides liquid sealing and gas imperviousness, said seal member
consisting essentially of a laminate disc of symmetrical,
multilayer structure comprising:
a middle layer made from a plastic material having a modulus of
rigidity of between about 1300 and 2200 MPa and exhibiting a gas
barrier effect;
two outer layers arranged on either side of said middle layer and
being made from a plastic material exhibiting a modulus of rigidity
of between about 100 and 300 MPa, and
between said middle layer and each of said outer layers, an
intermediate layer made of a plastic material of the same polymer
as the outer layers, but exhibiting a modulus of rigidity of
between about 1300 and 2200 MPa,
the said two outer layers each having a same thickness of between
300 and 550 .mu.m, said middle layer having a thickness of between
100 and 250 .mu.m; said intermediate layers each having a same
thickness of between 10 and 50 .mu.m and being joined to said outer
layers by calendaring while heated, and joined to said middle layer
with a polyurethane adhesive;
each of said outer layers having an outer surface which is exposed
so that both of said outer surfaces are capable of contacting and
sealing against a neck of a receptacle.
23. A screw cap according to claim 22, wherein each of said outer
layers consists of a sheet of polypropylene elastomer.
24. A receptacle which is sealed by a plastic closure screw cap
according to claim 22, said receptacle having a neck which is
directly contacted by one of said outer layers of said seal
member.
25. A screw cap according to claim 22, wherein said middle layer
consists of a sheet selected from the group consisting of
polyethylene terephthalate, polyamide, polyvinylidene chloride and
ethylene/vinyl alcohol.
26. A screw cap according to claim 25, wherein each of said
intermediate layers consists of a film of polypropylene.
Description
The present invention relates to a composite material for seals,
especially for screw caps, and to a seal produced from such a
material, ensuring leakproofing against liquids and imperviousness
to gases at the same time.
The substances generally employed for the production of
leakproofing seals for closure caps for bottles are flexible
substances which are relatively permeable to gases such as oxygen,
carbon dioxide and nitrogen. Similarly, thermoplastic substances
which are generally employed for injection moulding of closure caps
employing such seals are relatively permeable to gases. As a
result, the lifetime of the products packaged in bottles, flasks or
other receptacles closed with such caps is reduced because of the
gas exchanges through the caps.
These gas exchanges may, for example, result in an entry of oxygen
inside the receptacles, resulting in impairment of the organoleptic
properties of sensitive products such as fatty substances of
unsaturated type. They can also result in a loss of flavour in
aromatic substances. Finally, these gas exchanges can result in
undesirable external odours, related, for example, to the storage
environment of the products being trapped by the product contained
in the receptacle.
All these factors of deterioration of the organoleptic properties
of the packaged products argue in favour of an improvement in the
materials for use as seals for caps, especially plastic screw
caps.
The diverse composite materials employed hitherto to try and
combine, on the one hand, substances which have good barrier
properties to gases and other volatile substances and, on the other
hand, substances with a low modulus of rigidity, which are
therefore flexible and compressible, possessing good leakproofing
performance against liquids and an ability to compensate the
irregularities and tolerances of the necks of the receptacles, are
not entirely satisfactory.
The present invention consequently relates to a composite material
for seals especially for screw caps, a material which, while being
simple to manufacture and low in cost, meets the two contradictory
requirements of leakproofing against liquids and imperviousness to
gases. The invention further relates to a seal for caps, produced
in a simple manner from such a material.
The composite material forming the subject of the present invention
for seals especially for screw caps, ensuring leakproofing against
liquids and imperviousness to gases at the same time, comprises,
combined in a coherent multilayer structure, at least one middle
layer made of a plastic substance with a gas barrier effect, with a
high modulus of rigidity, (modulus of elasticity) and two outer
layers arranged on either side of this middle layer and consisting
of a plastic substance with a low modulus of rigidity, each of the
two outer layers having a thickness greater than the thickness of
the middle layer.
Preferably, the material may additionally comprise, between the
middle layer and the outer layer, an intermediate layer of a
substance of the same polymer type as the outer layer, but which
has a high modulus of rigidity.
The intermediate layers are advantageously joined to the middle
layer by adhesive bonding and the outer layers are joined to the
intermediate layers by calendering while heated.
The middle layer may, for example, consist of a sheet of PET, PA,
PVDC or E/VAL with a thickness of between 100 and 250 .mu.m.
Each outer layer may consist of a sheet of PP with a thickness of
between 300 and 550 .mu.m.
Each intermediate layer may consist of a film of PP with a
thickness of between 10 and 50 .mu.m.
The substance of the middle layer and the substance of the
intermediate layers may advantageously have a modulus of rigidity
in the same region, preferably a modulus of regidity of between
1300 and 2200 MPa.
The substance of the outer layers, for its part, may have a modulus
of rigidity of between approximately 100 and 300 MPa.
The intermediate layers are preferably joined to the middle layer
by adhesive bonding with the aid of polyurethane adhesive.
The seal forming the subject of the invention for a plastic cap,
especially a screw cap for closing receptacles, is produced by
cutting a disc from a composite material as defined above.
A more detailed description of an illustrative embodiment, which
does not limit the invention, will be given below, reference being
made to the attached diagrammatic drawings; in the drawings:
FIG. 1 shows a seal in accordance with the invention for a screw
cap for closing a flask;
FIG. 2 is a greatly enlarged section of a composite material in
accordance with the invention, for seals.
FIG. 3 is a section similar to FIG. 2, showing an alternative form
of the invention; and,
FIG. 4 is a view, partially in section, of a receptacle provided
with a cap and a seal according to the invention.
In FIG. 2, a seal 1 can be recognized, produced by cutting a disc
from a composite material and added into a screw cap 2 for closing
off the neck of a flask 3. The seal 1 is made of a composite
material performing the two functions of imperviousness to gases
and leakproofing against liquids, so that the cap 2 can be
manufactured, for example, by injection moulding starting with a
plastic substance, for example polypropylene, which may be chosen
without taking account of special requirements concerning the
imperviousness to gases and leakproofing against liquids.
The sealing material, as illustrated in FIG. 2, is made up of a
middle layer 4, of two intermediate layers 5 joined to the two
faces of the middle layer 4 by two layers of adhesive 6, and of two
outer layers 7 joined respectively to the intermediate layers
5.
The middle layer 4 consists of a sheet with a thickness of between
100 and 250 .mu.m made of a plastic substance with a gas barrier
effect, for example PET (poly(ethylene terephthalate)), PA
(polyamide), PVDC (poly(vinylidene chloride)) or E/VAL
(ethylene/vinyl alcohol), which has a modulus of rigidity of the
order of 1300 to 2200 MPa.
The intermediate layers 5 joined to the middle layer 4 by layers 6
of polyurethane adhesive may consist of PP films (made of
polypropylene) with a thickness of 10 to 50 .mu.m, with a high
modulus of rigidity (between 1300 and 2200 MPa).
Each of the outer layers 7 may consist of a flexible sheet, with a
thickness of between 300 and 550 .mu.m, made of polypropylene
elastomer with a low modulus of rigidity (100 and 300 MPa), the two
outer layers 7 being assembled with heating, by calendering while
heated, with the multilayer composite comprising the inner layer 4
and the two intermediate layers 5 joined to the inner layer 4 by
the two layers of adhesive 6. Each of the outer layers 7 has an
outer surface which is exposed, so both of these outer surfaces are
capable of contacting and sealing against the end of the neck of a
receptacle 3.
The different layers 4, 5, 7 of the composite material for seals
thus being a laminate which has a perfectly coherent structure,
despite the combination of a rigid substance with a gas barrier
effect and of a flexible substance with an effect of leakproofing
against liquids, this total cohesion enabling the material in
accordance with the invention to stop, at the seal produced from
this material, the gas exchanges both from the packaged product
towards the surrounding environment and from the surrounding
environment towards the packaged product.
Quite obviously, the embodiment shown and described has been given
merely by way of an illustrative example without any limitation
being implied, and many modifications and alternative forms are
possible within the scope of the invention.
Thus, the single middle layer 4 could be replaced, for example,
with a number of layers joined to each other, possibly made of
different materials.
The intermediate layers 5 are intended to simplify the bonding of
the outer layers 7 to the middle layer 1, a bonding which can be
performed by calendering the outer layers 4 onto the inner layer 1,
with heating, by virtue of the latter being lined with the two
intermediate layers 2 consisting of a substance of the same polymer
type as the outer layers 4. In an alternative form it would be
possible to eliminate the intermediate layers and to join the outer
layers to the middle layer directly by adhesive bonding.
Furthermore, substances other than those indicated above by way of
example could be employed for the different layers, provided that,
in one case, they exhibit the properties of imperviousness to gases
and, in the other, the properties of leakproofing against liquids,
the result being that these two apparently contraditory properties
are combined in the composite material incorporating these
different substances and the seal produced from this material.
* * * * *